This publication describes and summarizes the work of the MODARIA (modelling and data for radiological impact assessments) Programme Working Group 6. MODARIA was set up to continue the IAEA's activities in the field of testing, comparing and developing guidance on the application of models to assess radiation exposures to humans and radiological impacts on the environment. Different aspects of the MODARIA programme were addressed by ten working groups. MODARIA WG 6 had the remit of developing a common framework for addressing climate and environmental change in post-closure radiological assessments of solid radioactive waste disposal. The intention was to include a wide range of disposal facility types. An additional goal of WG 6 was to further develop the understanding of how the biosphere may develop from the present into the far future in a wide range of regional and local contexts relevant to the disposal of solid radioactive wastes. While the focus of MODARIA is dose assessment, the methodology and results of WG 6 may be valuable in a wider safety assessment context, for example for other types of facilities and sites.